1. Field of the Invention
The present invention relates to power supply circuits, and particularly to a power supply circuit for a central processing unit (CPU) in a computer.
2. Description of the Related Art
Energy consumption is an important issue for electronic products, such as personal computers. The CPU consumes a significant portion of the energy needed by a computer, and is therefore a logical target for minimizing energy consumption. The CPU having a power state indication (PSI) function will automatically reduce the voltage at the PSI pin of a voltage regulator module (VRM) in order to change the power supply, for example, from 5-phase to 3-phase when the CPU is idle. However, there are still many kinds of CPUs without the PSI function in the market.